Spark plug



Dec. 19, 1939. E. B. NOWOSIELSKI SPARK PLUG Original Filed Jan. 6, 1936 -IIL INVENTOR.

Edward 5. /V0w0s/eKs%/ K EY.

Patented Dec. 19, 1939 7 SPARK PLUG Edward B. Nowosielski, Bloomfield, N. J., assign-' or to Eclipse Aviation Corporation,

East

Orange, N. J a corporation of New Jersey Original application January 6, 1936, Serial No. 57,810. Divided and this application April 1, 1937, Serial No. 134,396-

3 Claims.

This invention relates to spark plugs, and

' more particularly to spark plugs of the type wherein the high tension circuit is not only insulated but. also shielded or screened to prevent 3 interference with the reception of signals in adjacent radio equipment.

Objects of the invention are to provide an improved method of shielding and insulating the high tension circuit of a spark plug, as well as a 10 novel structural combination of parts adapted to cooperate in the attainment of improved shielding and insulating properties.

For example, I provide, for application to a shielding element of the mica sleeve lined type,

an improved method of protecting the mica lining,

as well as a novel construction of adjacent parts to eliminate the possibility of fraying at the edges of the mica, notwithstanding repeated withdrawals and re-insertions of the connecting cable.

Another object is to secure the cable against the possibility of accidental withdrawal.

. Further purposes will appear in the speciiica-' tion and claims.

In the drawing I have illustrated the invention as applied to structures which I regard as conventional but representative of other forms which may be employed, and to which the invention may be applied without departure from the principles of the said invention, as disclosed herein.

Fig. l is a longitudinal sectional view of a device embodying the inventio iflg. 2 is a similar view of a second embodiment; and

Fig. 3 is a transverse end, or bottom plan view of the device of Fig. 2.

Referring first to Fig. 1, the apertured shielding element In is shown as an upward extension of the cylinder engaging base or shell ii, there being an intermediate polygonal portion 12 which receives the wrench or other tool forinsertion of the plug in the cylinder wall. The lower portion of the element 10 is also shown as provided with a polygonal section 13 facilitating its attachment to the shell II, but it is to be understood that the two members 10 and l I may be integral ii preferred.

In the space within the element 10, there is a cooling and ventilating chamber surrounding a 50. long thin metallic sleeve l5.lined with a tube 16 of rolled mica constituting the wall of a second annular chamber closed at its upper end by nonconducting sleeve or tube 11 having a metallic skirt l8 surrounding a pair of washers 28, 29 of brass or other compressible metallic material,

adapted to exert pressure upon a second insulating body 20 composed of a plurality of compressed mica washers, only part of which are visible in the drawing, and corresponding in structural arrangement to the conventional mica washer as- 5 sembly as illustrated, for example, at 20' in Fig.

2, and also in Hyland Patent No. 1,950,408, granted March 13, 1934.

Between the mica stack 20 and the center electrode I there is the usual rolled mica wrapper 23 10 which extends upwardly for almost the complete length of the spindle ll, the upper portion thereof being confined with the mica stack 20 when 'the upper hollow end 26 of the spindle is turned downwardly or upset upon' the compressible 15 metallic elements 29 and 28.

Within the hollow upper portion of the spindle I! there is provided a connecting pin 34 having an enlarged lower part 35 against which the upper end of coil spring 36 engages to urge the '20 chisel edged upper end of the pin into penetrating engagement with the stranded wire cable core 4l. As shown, the insulated cable 33 is adapted to pass through a metal'thimble or elbow 31, the latter having a flanged ring 38 soldered to its 5 lower end and pivotable within the detachable coupling member 52.threaded on the end of the shielding element 13. Before attaching the thimble 31 the spacer tube 11 of Bakelite, or

other 'rigid insulating construction, is inserted to 30 fit about electrode connection 34, with its skirt l3 telescoping with washer 28. The upper end of i the tube I1 is flanged, as at 44, to rest upon asbestos disc 45 and overlie the-upper edges of mica lining l6, and thus protect the mica lining 35 against fraying or bending out of position.

After passing the cable through the elbow thimble 31, a metal bracelet or spacing collar 43 p is pressed tightly about the rubber coating of the cable, at a point which is a pre-measured dis-- tance from the end of the cable. a

Coupling nut 52 and thimble 38, the latter being recessed to form an annular ledge 5|, are then moved forward intothe assembled relationship shown, wherein thimble 38 serves as a thrust 5 bearing to prevent withdrawal of theocable so long as coupling member 52 remains in place as shown. When the member 52 is unscrewed from the shielding element ill and drawn back (together with thimble 31, 3B) along the cable,

the latter may then-be withdrawn and inspected, but spacer tube l1 will remain in place due to the fact that the spun-over end SI of element Ill holds upper metallic washer 41 and flange 44 against displacement.

Preferably spacer tube I1 is grooved circumferentially, as indicated at 62, to facilitate heat dissipation and also to provide space for retention of a binding cement, if it is desired to apply such an auxiliary holding substance.

' In Fig. 2 the equivalent spacer tube I1 is shown as being held inplace by the flanged base 41' of thimble 38', the latter being a part of metal elbow 31', and in turn held by coupling member 52, when the latter is screwed in position on shield element l0. Bracelet 43 corresponds in function to bracelet 43 of Fig. 1, and is secured to the cable 33', and by virtue of its engagement with elbow 31, it prevents disturbance of the electrical connection between 40' and I4 so long as coupling nut 52' remains in place as shown. As in Fig. 1, the cable fits loosely within the spacer tube, so that with; drawal of the former does not necessarily disturb the latter.

Referring further to Fig. 2, the plug shell includes a cylinder engaging portion II, a heat radiating portion l2, and an upper portion H! which is internally threaded to receive coupling cap 52'. A cup shaped metallic ring 2| is suitably secured to the shell base II, as by spinning over the base tip in the manner indicated at 22, the ring being of an inner diameter sufiiciently large to permit passage therethrough of the longitudinally truncated cylindrical head por- "tion 26 of the central electrode spindle II; the

purpose of the truncating being to divide the surface of the electrode head into definite, angularly spaced spark paths to the ring 2l-there zbeing i'our such paths as shown.

The heat radiating portion l2 of the shell is internally threaded to receive a correspondingly threaded gland nut 21 adapted to exert sufficient pressure, both laterally and longitudinally, upon the externally flanged and tapered packing element 28 to cause deformation thereof into a gas tight sealing relationship with respect to both the mica enwrapped spindle l4 and the inner wall of the shell lI'-the packing 28 being of softer metal than that of which the nut 21 and shell H are composed. A metal washer 29 acts to compress the mica discs and 20" as well as the parts. l4, 2'! and 28, and the intervening mica wrapper 23, one against the other, the compression occurring during the act of upsetting the end 3| of the spindle ll over the top surface of the washer 29', the head portion 26 of the spindle acting to take the axial thrust during the process; it being understood that the assembly (exclusive of shell II) is braced against a suitable abutment during this compressing process. Then, as the assembly is threaded into the shell, further compression of the flange 34' of the packing 28 occurs, to complete the gas tight seal above referred to. Heat resistant baflie 35' (of asbestos or its equivalent) aids in the deflection of heat flow to the region of the radiating surfaces l2.

This application is a division of my Patent No. 2,079,561 based upon application No. 57,810, filed January 6, 1936.

What is claimed is:

1. In a spark plug for internal combustion engines, the combination with a central electrode, of a shell surrounding said electrode and having a cylinder engaging portion, a heat radiating portion, and a cap receiving portion, an insulating wrapper surrounding said central electrode, a flanged packing element surrounding said wrapper and engaging the'heat radiating portion of said shell for transfer of heat thereto, means engageable with said packing element to establish a gas-tight joint of high heat conductivity between said central electrode and said heat radiating portion of said shell, and a free fitting insulator carried by a portion of said last named means, and terminating in a plane adjacent the said cap receiving portion of the shell.

2. In a spark plug for internal combustion engines, the combination with a central electrode, of a shell surrounding said electrode and having a cylinder engaging portion, a heat radiating portion, and a cap receiving portion, an insulating wrapper surrounding said central electrode, a flanged packing element surrounding said wrapper and having peripheral engagement with the heat radiating portion of said shell for transfer of heat thereto, means engageable with said packing element to establish a gas-tight joint of high heat conductivity between said central electrode and said heat radiating portion of said shell, a free fitting insulator carried by a portion of said last named means, and terminating in a plane adjacent the said cap receiving portion of the shell, and means engageable with both said' cap receiving portion and said insulator to retain the ignition cable in current conducting relation to said central electrode.

3. In a spark plug for internal combustion engines, the combination with a central electrode,

of a shell surrounding said electrode and having a cylinder engaging portion and a cap receiving portion, a packing element surrounding said central electrode, means engageable with said packing element to establish a gas-tight joint between said central electrode and said shell, a free-fitting insulator carried by a portion of said last-named means, and terminating adjacent the said cap receiving portion of the shell, and means engageable with both said cap receiving portion and said insulator to retain an ignition cable in current conducting relation to said central electrode,

EDWARD B. NOWOSIELSKI. 

